| Jun 5, 2026 | Arabidze | 1–0 | Sieber | Round 11: Arabidze, Meri - Sieber, Fiona | English Opening: Anglo-Indian Defense | |
| Jun 4, 2026 | Sieber | ½–½ | Wagner | Round 10: Sieber, Fiona - Wagner, Dinara | Sicilian Defense: Nyezhmetdinov-Rossolimo Attack | |
| Jun 3, 2026 | Milliet | 0–1 | Sieber | Round 9: Milliet, Sophie - Sieber, Fiona | Catalan Opening: Open Defense | |
| Jun 2, 2026 | Sieber | ½–½ | Efroimski | Round 8: Sieber, Fiona - Efroimski, Marsel | French Defense: Advance Variation, Euwe Variation | |
| Jun 1, 2026 | Khukhashvili | 0–1 | Sieber | Round 7: Khukhashvili, Sopiko - Sieber, Fiona | Sicilian Defense: Chekhover Variation | |
| May 30, 2026 | Sieber | ½–½ | Avramidou | Round 6: Sieber, Fiona - Avramidou, Anastasia | Sicilian Defense: Pin Variation | |
| May 29, 2026 | Bivol | 1–0 | Sieber | Round 5: Bivol, Alina - Sieber, Fiona | Sicilian Defense: Delayed Alapin Variation, with e6 | |
| May 28, 2026 | Sieber | 1–0 | Brunello | Round 4: Sieber, Fiona - Brunello, Marina | Sicilian Defense: Moscow Variation | |
| May 27, 2026 | Mkrtchian | ½–½ | Sieber | Round 3: Mkrtchian, Lilit - Sieber, Fiona | English Opening: Agincourt Defense, Wimpy System | |
| May 26, 2026 | Sieber | ½–½ | Klek | Round 2: Sieber, Fiona - Klek, Hanna Marie | English Opening: King's English Variation, Kramnik-Shirov Counterattack | |
| May 25, 2026 | Saltkhutsishvili | 0–1 | Sieber | Round 1: Saltkhutsishvili, Sara - Sieber, Fiona | Sicilian Defense: Najdorf Variation, Adams Attack | |
| Apr 19, 2026 | Sieber | 1–0 | Hund | Round 11: Sieber, Fiona - Hund, Barbara | Scotch Game: Mieses Variation | |
| Apr 18, 2026 | Sieber | 0–1 | Safarli | Round 10: Sieber, Fiona - Safarli, Josefine | Ruy Lopez: Closed, Martinez Variation | |
| Apr 17, 2026 | Sieber | ½–½ | Manko | Round 5: Sieber, Fiona - Manko, Mariia | Sicilian Defense: Nyezhmetdinov-Rossolimo Attack, Fianchetto Variation | |
| Apr 5, 2026 | Lie | 1–0 | Sieber | Fagernes International 2026 | English Opening: King's English Variation, Two Knights Variation | |
| Apr 4, 2026 | Sieber | ½–½ | Banerjee | Fagernes International 2026 | French Defense: Classical Variation | |
| Apr 3, 2026 | Kreken | ½–½ | Sieber | Fagernes International 2026 | Grünfeld Defense: Stockholm Variation | |
| Apr 2, 2026 | Brynell | ½–½ | Sieber | Fagernes International 2026 | Queen's Indian Defense: Fianchetto Variation, Nimzowitsch Variation | |
| Apr 1, 2026 | Sieber | 0–1 | Fiskaaen | Fagernes International 2026 | Four Knights Game: Scotch Variation Accepted | |
| Apr 1, 2026 | Debmisra | 0–1 | Sieber | Fagernes International 2026 | Ruy Lopez: Morphy Defense, Wormald Attack | |
| Mar 31, 2026 | Sieber | ½–½ | Elmi | Fagernes International 2026 | Sicilian Defense: Godiva Variation | |
| Mar 30, 2026 | Sieber | 1–0 | Sivaparan | Fagernes International 2026 | Sicilian Defense: Najdorf Variation | |
| Mar 24, 2026 | Ghosh | 1–0 | Sieber | Fagernes International 2026 | English Opening: King's English Variation | |
| Mar 14, 2026 | Ciolacu | 1–0 | Sieber | Round 8: Ciolacu, Alessia-Mihaela - Sieber, Fiona | Queen's Pawn Game | |
| Mar 1, 2026 | Sieber | 0–1 | Korchynskyi | 2. Bundesliga Nord | Caro-Kann Defense: Advance Variation | |
| Feb 22, 2026 | Gaal | ½–½ | Sieber | FB1 2526 Hamburger SK - Rodewischer Scha | Grünfeld Defense | |
| Feb 21, 2026 | Sieber | 1–0 | Braeutigam | FB1 2526 Rodewischer Schachmiezen - TuRa | Caro-Kann Defense: Advance Variation, Botvinnik-Carls Defense | |
| Nov 30, 2025 | Klek | 0–1 | Sieber | Round 4: Klek, Hanna Marie - Sieber, Fiona | Italian Game: Two Knights Defense, Modern Bishop's Opening | |
| Nov 29, 2025 | Sieber | 0–1 | Arabidze | Round 3: Sieber, Fiona - Arabidze, Meri | Philidor Defense: Lion Variation, Shirov Gambit | |
| Nov 23, 2025 | Alghawi | 1–0 | Sieber | Round 9: Alghawi, Abdullah - Sieber, Fiona | King's Indian Attack: Symmetrical Defense | |
| Nov 23, 2025 | Sieber | 0–1 | Tupac Yupanqui Herrera | Round 8: Sieber, Fiona - Tupac Yupanqui Herrera, Daniel | Sicilian Defense: Four Knights Variation, Exchange Variation | |
| Nov 23, 2025 | Fromm | 1–0 | Sieber | Round 7: Fromm, Marius - Sieber, Fiona | Sicilian Defense: French Variation | |
| Nov 23, 2025 | Sieber | 1–0 | Huth | Round 6: Sieber, Fiona - Huth, Kevin | French Defense: Advance Variation, Paulsen Attack | |
| Nov 23, 2025 | Wilk | 0–1 | Sieber | Round 5: Wilk, Clemens - Sieber, Fiona | Trompowsky Attack | |
| Nov 23, 2025 | Sieber | 1–0 | Enxing | Round 4: Sieber, Fiona - Enxing, Philemon | French Defense: Advance Variation, Milner-Barry Gambit, Hector Variation | |
| Nov 23, 2025 | Roberts | 0–1 | Sieber | Round 3: Roberts, Ashley - Sieber, Fiona | Sicilian Defense: Delayed Alapin Variation, with e6 | |
| Nov 23, 2025 | Sieber | 0–1 | Wohlfahrt | Round 2: Sieber, Fiona - Wohlfahrt, Jonas | Modern Defense: Standard Defense | |
| Nov 23, 2025 | Albus | 0–1 | Sieber | Round 1: Albus, Alexander - Sieber, Fiona | Indian Defense: Knights Variation | |
| Nov 22, 2025 | Sieber | 1–0 | Doedens | Round 9: Sieber, Fiona - Doedens, Julian | Sicilian Defense: Four Knights Variation, Exchange Variation | |
| Nov 22, 2025 | Hassemeier | 1–0 | Sieber | Round 8: Hassemeier, Mika - Sieber, Fiona | Queen's Indian Accelerated | |
| Nov 22, 2025 | Sieber | 1–0 | Kraft | Round 7: Sieber, Fiona - Kraft, Adrian | Modern Defense: Lizard Defense, Mittenberger Gambit | |
| Nov 22, 2025 | Alghawi | 0–1 | Sieber | Round 6: Alghawi, Abdullah - Sieber, Fiona | King's Indian Attack: French Variation | |
| Nov 22, 2025 | Sieber | 1–0 | Kosak | Round 5: Sieber, Fiona - Kosak, Karolina | Sicilian Defense: Moscow Variation, Main Line | |
| Nov 22, 2025 | Henning | 1–0 | Sieber | Round 4: Henning, Marvin - Sieber, Fiona | Sicilian Defense: Scheveningen Variation, Modern Variation | |
| Nov 22, 2025 | Sieber | 1–0 | Born | Round 3: Sieber, Fiona - Born, Jonathan | Scotch Game: Mieses Variation | |
| Nov 22, 2025 | Arnold | ½–½ | Sieber | Round 2: Arnold, Leander - Sieber, Fiona | English Opening: Symmetrical Variation | |
| Nov 22, 2025 | Sieber | 1–0 | Miled | Round 1: Sieber, Fiona - Miled, Zied | Sicilian Defense: Nyezhmetdinov-Rossolimo Attack | |
| Nov 15, 2025 | Alexakis | 1–0 | Sieber | Round 7: Alexakis, Dimitris - Sieber, Fiona | Sicilian Defense: Scheveningen Variation, Modern Variation | |
| Nov 15, 2025 | Petrovskiy | 1–0 | Sieber | Round 5: Petrovskiy, Vadym - Sieber, Fiona | Sicilian Defense: Four Knights Variation, Exchange Variation | |
| Nov 14, 2025 | Sieber | 0–1 | Petersen | Round 11 & Quarterfinals Armageddon: Sieber, Fiona - Petersen, Marcel | Scotch Game: Mieses Variation | |
| Nov 14, 2025 | Stein | 1–0 | Sieber | Round 4: Stein, Robert - Sieber, Fiona | English Opening: Symmetrical Variation, Four Knights Variation | |
| Sep 21, 2025 | Sieber | 0–1 | Bluhm | Round 2: Sieber, Fiona - Bluhm, Sonja Maria | Ruy Lopez: Morphy Defense, Fianchetto Defense Deferred | |
| Sep 20, 2025 | Czaeczine | 0–1 | Sieber | Round 1: Czaeczine, Anne - Sieber, Fiona | Sicilian Defense: Four Knights Variation, Exchange Variation | |
| Jun 26, 2025 | Papp | 0–1 | Sieber | Rigó János Memorial IMB | Nimzo-Indian Defense: Rubinstein System, Rubinstein Variation | |
| Jun 25, 2025 | Sieber | ½–½ | Polyik | Rigó János Memorial IMB | French Defense: McCutcheon Variation, Lasker Variation | |
| Jun 25, 2025 | Pribelszky | 1–0 | Sieber | Rigó János Memorial IMB | King's Indian Attack: Symmetrical Defense | |
| Jun 24, 2025 | Sieber | 1–0 | Tan | Rigó János Memorial IMB | Sicilian Defense: Najdorf Variation, Lipnitsky Attack | |
| Jun 23, 2025 | Jakab | 1–0 | Sieber | Rigó János Memorial IMB | Nimzo-Indian Defense: Classical Variation, Noa Variation | |
| Jun 23, 2025 | Sieber | 0–1 | Fodor | Rigó János Memorial IMB | Sicilian Defense: Nyezhmetdinov-Rossolimo Attack, Fianchetto Variation | |
| Jun 22, 2025 | Halak | ½–½ | Sieber | Rigó János Memorial IMB | Sicilian Defense: Alapin Variation, Barmen Defense | |
| Jun 21, 2025 | Sieber | 0–1 | Vuelban | Rigó János Memorial IMB | Nimzowitsch Defense: Williams Variation | |
| Jun 20, 2025 | Sieber | ½–½ | Swarna Nihal | Rigó János Memorial IMB | Catalan Opening: Closed | |
| Jun 14, 2025 | Prishita Gupta | 1–0 | Sieber | Round 9: Prishita Gupta - Sieber, Fiona | Scotch Game: Romanishin Variation | |
| Jun 11, 2025 | Sieber | 0–1 | Fedorovsky | Round 6: Sieber, Fiona - Fedorovsky, Michael | Sicilian Defense: Dragon Variation, Yugoslav Attack, Modern Line | |
| Jun 9, 2025 | Sieber | 0–1 | Raghav V | Round 4: Sieber, Fiona - Raghav V | Sicilian Defense: Taimanov Variation, Bastrikov Variation, English Attack | |
| Jun 8, 2025 | Sieber | 0–1 | Kostov | Round 2: Sieber, Fiona - Kostov, Deyan Samuil | Sicilian Defense: Taimanov Variation, Bastrikov Variation, English Attack | |
| Jun 8, 2025 | Agarwal | * | Sieber | Round 1: Agarwal, Amaya - Sieber, Fiona | ? | |
| May 25, 2025 | Sieber | 1–0 | Schulze | Round 2: Sieber, Fiona - Schulze, Lara | Scotch Game: Mieses Variation | |
| May 25, 2025 | Wilmink | 0–1 | Sieber | Round 1: Wilmink, Anna - Sieber, Fiona | Sicilian Defense | |
| May 24, 2025 | Sieber | ½–½ | Doll | Round 27: Sieber, Fiona - Doll, Rebecca | Ruy Lopez: Morphy Defense | |
| May 24, 2025 | Malinowsky | 0–1 | Sieber | Round 26: Malinowsky, Celina - Sieber, Fiona | Sicilian Defense: French Variation | |
| May 24, 2025 | Sieber | 1–0 | Villip | Round 25: Sieber, Fiona - Villip, Sofiia | French Defense: Classical Variation, Steinitz Variation | |
| May 24, 2025 | Dolzhykova | 0–1 | Sieber | Round 24: Dolzhykova, Kateryna - Sieber, Fiona | Sicilian Defense: Four Knights Variation, Exchange Variation | |
| May 24, 2025 | Sieber | 1–0 | Butenandt | Round 23: Sieber, Fiona - Butenandt, Svenja | Modern Defense: Standard Line | |
| May 24, 2025 | Wagner | 1–0 | Sieber | Round 22: Wagner, Dinara - Sieber, Fiona | Queen's Indian Defense: Kasparov-Petrosian Variation, Main Line | |
| May 24, 2025 | Sieber | 1–0 | Pfau | Round 21: Sieber, Fiona - Pfau, Beate | Sicilian Defense: Hyperaccelerated Fianchetto | |
| May 24, 2025 | Anissimova | 0–1 | Sieber | Round 20: Anissimova, Mariya - Sieber, Fiona | King's Indian Attack: French Variation | |
| May 24, 2025 | Sieber | 0–1 | Novikova | Round 19: Sieber, Fiona - Novikova, Marharyta | Scandinavian Defense: Modern Variation | |
| May 24, 2025 | Noll | 0–1 | Sieber | Round 18: Noll, Sonja - Sieber, Fiona | Sicilian Defense: Alapin Variation | |
| May 24, 2025 | Sieber | 1–0 | Khrapko | Round 17: Sieber, Fiona - Khrapko, Marharyta | Sicilian Defense: Nyezhmetdinov-Rossolimo Attack | |
| May 24, 2025 | Voicu-Jagodzinsky | 1–0 | Sieber | Round 16: Voicu-Jagodzinsky, Carmen - Sieber, Fiona | Indian Defense: London System | |
| May 24, 2025 | Sieber | 1–0 | Bursan | Round 15: Sieber, Fiona - Bursan, Ana-Maria | French Defense: Winawer Variation, Bogoljubow Variation | |
| May 24, 2025 | Heutling | 0–1 | Sieber | Round 14: Heutling, Elina - Sieber, Fiona | Ruy Lopez: Morphy Defense, Cozio Defense | |
| May 24, 2025 | Sieber | 0–1 | Sickmann | Round 13: Sieber, Fiona - Sickmann, Lisa | Sicilian Defense: Four Knights Variation | |
| May 24, 2025 | Koldunov | 0–1 | Sieber | Round 12: Koldunov, Elena - Sieber, Fiona | Sicilian Defense: Kramnik Variation | |
| May 24, 2025 | Sieber | 1–0 | Brandt | Round 11: Sieber, Fiona - Brandt, Carina | French Defense: Winawer Variation, Bogoljubow Variation | |
| May 24, 2025 | Braeuer | 0–1 | Sieber | Round 10: Braeuer, Vanessa - Sieber, Fiona | Sicilian Defense: Snyder Variation | |
| May 24, 2025 | Sieber | 1–0 | Roessler | Round 6: Sieber, Fiona - Roessler, Ulrike | Sicilian Defense: Najdorf Variation, Freak Attack | |
| May 24, 2025 | Neumann | 0–1 | Sieber | Round 5: Neumann, Helena - Sieber, Fiona | Hungarian Opening | |
| May 24, 2025 | Sieber | ½–½ | Morio | Round 4: Sieber, Fiona - Morio, Estelle | Philidor Defense: Lion Variation | |
| May 24, 2025 | Schulze | 0–1 | Sieber | Round 3: Schulze, Lara - Sieber, Fiona | Indian Defense | |
| May 23, 2025 | Sieber | 0–1 | Kosovska | Round 9: Sieber, Fiona - Kosovska, Olena | Sicilian Defense: Dragon Variation, Yugoslav Attack, Modern Line | |
| May 23, 2025 | Wilke | 0–1 | Sieber | Round 7: Wilke, Ronja - Sieber, Fiona | Italian Game: Scotch Gambit, Max Lange Attack | |
| May 14, 2025 | Sieber | ½–½ | Schulze | Round 2: Sieber, Fiona - Schulze, Lara | King's Indian Attack: Spassky Variation | |
| May 14, 2025 | Sieber | 0–1 | Schneider | Round 4: Sieber, Fiona - Schneider, Jana | Scotch Game: Malaniuk Variation | |
| May 14, 2025 | Sieber | ½–½ | Wagner | Round 6: Sieber, Fiona - Wagner, Dinara | Sicilian Defense: Najdorf Variation | |
| May 14, 2025 | Sieber | 0–1 | Peglau | Round 8: Sieber, Fiona - Peglau, Charis | French Defense: Advance Variation, Euwe Variation | |
| May 14, 2025 | Sickmann | ½–½ | Sieber | Round 1: Sickmann, Lisa - Sieber, Fiona | Ruy Lopez: Morphy Defense, Cozio Defense | |
| May 14, 2025 | Dolzhykova | 0–1 | Sieber | Round 3: Dolzhykova, Kateryna - Sieber, Fiona | Sicilian Defense: French Variation | |
| May 14, 2025 | Klek | ½–½ | Sieber | Round 5: Klek, Hanna Marie - Sieber, Fiona | Italian Game: Two Knights Defense, Modern Bishop's Opening | |